Og views group audience filter validation doesn't manage multiple arguments

Problem/Motivation

Hi!
I created a view that filter contents by their Group Audience, so I added a contextual filter on "Content: Group Audience"
and I checked the "Specify validation criteria" with OG Group as validator, Node as Group type and "Allow multiple values" box in the "More" section of the filter settings.

The view worked fine until the Drupal core update from 7.36 to 7.37 (here release notes), then it broke due to the add to entity.inc (line 186) of

    // Ensure integer entity IDs are valid.
    if (!empty($ids)) {
      $this->cleanIds($ids);
    }

Searching a bit into the code I found that the entity.inc was called by entity_load_single() in the validate_argument() of og_plugin_argument_validate_group.inc (line 37). The issue is due to from validation that doesn't manage correctly multiple arguments:

  function validate_argument($argument) {
    if (empty($argument)) {
      return;
    }
    $group_type = $this->options['group_type'];
    $entity = entity_load_single($group_type, $argument);
    if (!$entity || !og_is_group($group_type, $entity)) {
      return FALSE;
    }

    $this->argument->argument = $argument;
    $this->argument->validated_title = entity_label($group_type, $entity);
    return TRUE;
  }

Proposed resolution

My propose is to upgrade the validate_argument of og_plugin_argument_validate_group.inc to correctly manage multiple arguments, as it already does with single arg.